JP2007088442A - Piezoelectric element, liquid ejection head employing it, and liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric suitable as a piezoelectric actuator excellent in displacement ability, efficiency and use durability and especially applicable to a transverse oscillation mode piezoelectric actuator suitable for micromachining. <P>SOLUTION: The piezoelectric element comprises a piezoelectric, and a pair of electrodes touching the piezoelectric wherein the piezoelectric constants d<SB>33</SB>and d<SB>31</SB>of the piezoelectric satisfy relation (I); 0.1≤¾d<SB>33</SB>/d<SB>31</SB>¾≤1.8 (I). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric element, a liquid discharge head using the same, and a liquid discharge apparatus.

  The piezoelectric element is a functional element utilizing a piezoelectric phenomenon, that is, a piezoelectric effect in which an electric field is generated when a stress is applied to the piezoelectric material, or a reverse piezoelectric effect in which a stress is generated when an electric field is applied to the piezoelectric material.

  As an element using the piezoelectric effect, a piezoelectric ignition element, an acceleration sensor element, a gyro angular velocity sensor element, a strain gauge element or the like is used. In addition, as an element using the inverse piezoelectric effect, it is used for a precision driving element such as an ultrasonic vibration element, a speaker, and a stage of a scanning probe microscope (SPM). Furthermore, in recent years, it has been used for ejection drive elements of inkjet heads, and further, drive elements such as MEMS.

  For piezoelectric elements that use the inverse piezoelectric effect and have the function of fine precision driving, the piezoelectric element is roughly divided into two in the direction of taking out strain and stress generated by the inverse piezoelectric effect with respect to the direction in which the electric field is applied. Can be classified.

First, a d ₃₃ mode type or a longitudinal vibration mode type utilizing strain-stress (longitudinal effect) parallel to the direction in which the addition of the electric field direction (d ₃₃ direction). On the other hand, it is a d ₃₁ mode type or a transverse vibration mode type that uses strain / stress (longitudinal effect) in the vertical plane direction (d ₃₁ direction) with respect to the direction in which the electric field is applied. There is also the case of using a strain-stress shear direction (d ₁₅ direction) to the direction an electric field is applied, but can be divided by the strain direction to take out the predominantly transverse vibration mode type, the longitudinal vibration mode type.

Here, the vertical vibration mode, especially when using the d ₃₃ direction of the strain-stress to the piezoelectric actuator, taking advantage of displacement due to a direction parallel to the stress-strain with respect to the input electric field direction in the input electric field direction of the piezoelectric material and Become. The displacement amount at this time can only be obtained at most about 1% of the thickness of the piezoelectric material to which the input electric field is applied, due to the characteristics of the piezoelectric material. Therefore, in order to obtain a larger amount of displacement, it is necessary to increase the thickness in the direction in which the electric field is applied. However, when the thickness is increased, in order to obtain a displacement according to the performance of the piezoelectric material, it is necessary to apply an electric field having a strength corresponding to the thickness, and there is a problem that the drive voltage must be increased. Therefore, in order to solve the problem, a configuration has been proposed in which a piezoelectric body is stacked in a direction perpendicular to the displacement extraction direction with an electrode for applying a driving electric field interposed therebetween to suppress the driving voltage low.

On the other hand, when the transverse vibration mode, in particular, the strain / stress in the d ₃₁ direction is used for the piezoelectric actuator, the stress / strain in the plane direction perpendicular to the input electric field direction of the piezoelectric body is used with respect to the input electric field direction. At this time, the displacement amount of the piezoelectric body itself is generally smaller than that in the longitudinal vibration mode. However, in the d ₃₁ mode, the substrate is bent by constraining the piezoelectric element to the substrate and the piezoelectric body is distorted in the transverse vibration mode. As a result, even if the thickness in the direction in which the electric field is applied is small, a large displacement is caused. It is possible to take it out. In addition, since the drive voltage can be set low because the thickness in the direction in which the electric field is applied is thin, a bending mode type piezoelectric actuator is generally employed.

  These methods are appropriately selected according to the use of the piezoelectric actuator.

However, when applied to a high-density, multi-nozzle inkjet head that can be applied to a precision drive source of MEMS having a fine structure in recent years and an inkjet apparatus for which high speed and high image quality are required, the following can be said. In other words, a bending mode type piezoelectric actuator using a d ₃₁ mode transverse vibration mode in which a piezoelectric material that can be directly synthesized on a substrate including a drive power supply electrode using a thin film deposition technique that can be finely processed can be used. Adoption has become effective.

  However, since a piezoelectric material synthesized and formed using thin film deposition technology is formed in a state of being constrained to a substrate including a drive power supply electrode, its piezoelectric characteristics are similar to that of a piezoelectric material such as bulk ceramics. There is a problem that the piezoelectric characteristics are not sufficient in comparison.

Here, regarding the relationship between the piezoelectric constants d ₃₃ and d ₃₁ , for example, in bulk ceramics, dZ for each composition of PZT (Pb (Zr, Ti) O ₃ ) with a Zr / Ti ratio changed in Non-Patent Document 1. _33, d ₃₁ is described. A graph plotting the values is shown in FIG. In FIG. 2, the straight line passing through the origin of the graph is a straight line that is linearly approximated based on the plotted data, and indicates a slope d ₃₃ / | d ₃₁ | = 2.5.

In Patent Document 1, as a material suitable for an underwater transducer (hydrophone) using the inverse piezoelectric effect / piezoelectric effect, the piezoelectric constant dh under hydrostatic pressure is obtained by making d ₃₁ substantially zero;
dh = d ₃₃ + 2 × d ₃₁
There has been proposed a piezoelectric material that combines organic and inorganic materials with a large thickness.

Incidentally, d ₃₁ determination can be performed using a unimorph type cantilever method. The relationship between the displacement amount of the unimorph type cantilever and the input voltage V at this time is described in Non-Patent Document 2, and the physical property value of the relational expression is described in Non-Patent Document 3.
Japanese Patent No. 3256254 Ceramic Dielectric Engineering Page334 (written by Kiyoshi Okazaki) JG Smith, W. Choi, The constituent equations of piezoelectric heterogeneous bimorph, IEEE trans.Ultrason. Ferro. Freq. Control 38 (1991) 256-270. W.Cao, Full set Material Properties of Multi-Domain and Single-domain (1-x) Pb (Mg1 / 3Nb2 / 3) O3-xPbTiO3 and (1-x) Pb (Zn1 / 3Nb2 / 3) O3-xPbTiO3 SingleCrystals and the Principle of Domain Engineering Method, Piezoelectric Single Crystals and Their Application (p236-256), Edited S. Trolier-Mckinstry, LE Cross, Y. Yamashita.

  INDUSTRIAL APPLICABILITY As described above, the present invention provides a piezoelectric body suitable as a piezoelectric actuator excellent in displacement capability, efficiency, and usage durability, and can be suitably used in a lateral vibration mode piezoelectric actuator particularly suitable for fine structure processing. An object is to provide a piezoelectric body.

  In order to achieve the above object, the present inventors have synthesized various piezoelectric materials and studied film formation, and as a result, the following inventions have been achieved.

The object is to provide a piezoelectric element having a piezoelectric body and a pair of electrodes in contact with the piezoelectric body, with respect to piezoelectric constants d ₃₃ and d ₃₁ of the piezoelectric body, the following relational expression (I)
0.1 ≦ | d ₃₃ / d ₃₁ | ≦ 1.8 (I)
This is achieved by a piezoelectric element characterized by satisfying

  In addition, the present invention is a liquid discharge head including the piezoelectric element, and a liquid discharge apparatus including the liquid discharge head.

According to the present invention, excellent displacement capability as the piezoelectric element, since d ₃₃ direction of displacement is small, can be utilized efficiently actuator displacement. Furthermore, it is possible to provide a piezoelectric body excellent in use durability, particularly a piezoelectric body that can be suitably used for a transverse vibration mode piezoelectric actuator suitable for fine structure processing.

[Piezoelectric element]
A configuration of a piezoelectric element using the transverse vibration mode of the present embodiment will be described with reference to FIG.

  The piezoelectric element according to the present embodiment is a piezoelectric element having a piezoelectric body and a pair of electrodes in contact with the piezoelectric body. In terms of its functional aspect, it has at least a strain / stress generation part composed of two electrodes (upper electrode and lower electrode) for supplying a driving voltage and a piezoelectric body sandwiched between them. Yes. Furthermore, it can also be set as the structure which has a diaphragm part comprised with the diaphragm provided on one of the electrodes (it uses as a lower electrode for convenience in this specification).

  FIGS. 1A-1 and 1A-2 are diagrams illustrating a basic configuration of a unimorph type cantilever (cantilever) which is an example of a piezoelectric actuator using a transverse vibration mode of a piezoelectric body. (A-1) is a side view, and (A-2) is a top view. 101 is a diaphragm, 102 is a lower electrode, 103 is a piezoelectric body, 104 is an upper electrode, and 105 is a cantilever fixing portion. When a voltage is applied between the upper and lower electrodes 102 and 104, the piezoelectric body 103 expands and contracts in the surface direction, so that the open end of the cantilever vibrates up and down. Such a piezoelectric element (unimorph type cantilever) is used, for example, for driving a mirror of an optical scanner.

  FIGS. 1B-1 and 1B-2 are diagrams illustrating a basic configuration of a unimorph actuator that is an example of a piezoelectric actuator using a transverse vibration mode of a piezoelectric body. (B-1) is a side view, and (B-2) is a top view. Reference numeral 111 denotes a diaphragm, 112 denotes a lower electrode, 113 denotes a piezoelectric body, 114 denotes an upper electrode, and 115 denotes an actuator holding base. When a voltage is applied between the upper and lower electrodes 112 and 114, the piezoelectric body 113 expands and contracts in the plane direction, so that the vibration plate 111 vibrates up and down with the actuator central portion as a maximum displacement. Such a piezoelectric element is used for an inkjet head, for example.

  Next, components related to the piezoelectric element of the present embodiment, vocabulary described in the present specification, an ink jet head to which the piezoelectric element of the present embodiment can be suitably applied, and an ink jet printer using the ink jet head will be described.

[Piezoelectric body]
The piezoelectric body used in the present embodiment has the following relational expression (I) for the piezoelectric constants d ₃₃ and d ₃₁ :
0.1 ≦ | d ₃₃ / d ₃₁ | ≦ 1.8 (I)
It is characterized by satisfying.

  When an electric field is applied to a piezoelectric body, strain and stress are generated according to the applied electric field. The piezoelectric constant indicates the ability to distort the electric field. Generally, when discussing the inverse piezoelectric effect as in this embodiment, the unit is [pm / V] and [pC / N] when discussing the piezoelectric effect.

Here, the subscript notation of d ₃₃ and d ₃₁ indicates the direction in which the electric field is applied when the first three axes 1, 2 and 3 are defined, and the second subscript is the direction of distortion. Indicates.

In general, | d ₃₃ / d ₃₁ | is empirically said to be in the range of 2 <| d ₃₃ / d ₃₁ | <3 for various piezoelectric materials.

In addition, attempts have been made to substantially reduce d ₃₁ to zero as a piezoelectric material for an underwater transducer in which distortion in the d ₃₁ direction becomes noise. That | d ₃₃ / d ₃₁ | Attempts to develop ≧ 3 become organic / inorganic composite piezoelectric material have been made, the organic / inorganic by selecting a composite piezoelectric material, the underwater transducer effective piezoelectric the absolute value of the constant d ₃₃ was causing adverse effect would decrease.

However, in order to achieve the above object, the present inventors have selected the pulse MOCVD method as the piezoelectric material synthesis / film formation means and studied the synthesis / film formation method. It has been found that the piezoelectric body is out of the region showing the relative relationship between ₃₃ and d ₃₁ . And it discovered that the piezoelectric material was suitable for the piezoelectric actuator using a transverse vibration mode.

In particular,
0.1 ≦ | d ₃₃ / d ₃₁ | ≦ 1.8 (I)
Then, it is suitable as a piezoelectric body for a piezoelectric actuator that uses a transverse vibration mode.

When the relationship between the piezoelectric constants d ₃₃ and d ₃₁ is in the range of | d ₃₃ / d ₃₁ | ≦ 1.8, the displacement amount in the transverse vibration mode is large and the displacement in the longitudinal vibration mode is suppressed. Actuator displacement can be used efficiently. Furthermore, it becomes possible to provide a piezoelectric element with little deterioration in characteristics even when used for a long time.

Although the reason why the piezoelectric body according to the present embodiment has the above-mentioned effect is not clear, in the process of forming the piezoelectric body on the film formation substrate, the piezoelectric material first has a nucleus serving as a film formation starting point on the substrate. It is formed on the film formation substrate and scattered. Then, a process of forming a piezoelectric film by growing from the nucleus in the surface direction and thickness direction on the film formation substrate is performed. At this time, the piezoelectric material starting to grow from adjacent nuclei associates in the surface direction to form a film state. In this process, the bonding state greatly affects the relative relationship of piezoelectric constants | d ₃₃ / d ₃₁ |. I think. In the piezoelectric body according to this embodiment, pulse MOCVD is selected as a film forming method, and the bonding state of piezoelectric materials grown from adjacent nuclei in the film growth process is controlled by precisely adjusting the pulse time interval. it can. By doing so, it is considered that the piezoelectric body according to the present embodiment can be obtained.

The relationship between the piezoelectric constants d ₃₃ and d ₃₁ is | d ₃₃ / d ₃₁ | <0.1, which is an area that can be achieved only when the absolute values of d ₃₃ and d ₃₁ are small. It is not suitable for a piezoelectric body for a piezoelectric actuator that uses a transverse vibration mode. The relationship between the piezoelectric constants d ₃₃ and d ₃₁ is more preferably 0.14 ≦ | d ₃₃ / d ₃₁ | ≦ 1.5.

  The piezoelectric body according to the present embodiment can be obtained by adjusting the film formation method for each material, specifically, the pulse time interval in the pulse MOCVD method.

  In the present embodiment, PZT / relaxer piezoelectric materials are particularly preferable. However, these materials are a group of materials that are particularly easy to control the bonding state described above.

  It is preferable that the film thickness of the piezoelectric body is 1 μm or more and 10 μm or less because the effective electric field for driving the piezoelectric actuator can be appropriately set without using a special driving power source when used for a piezoelectric actuator using the transverse vibration mode. .

[PZT and relaxor piezoelectric materials]
The PZT-based material described in this specification is a general formula Pb (Zr _x , Ti _1-x ) O ₃ [0 <x <1], and Pb, Zr, or Ti is appropriately added to the main component. An element to be substituted may be added. Examples of the element to be added include La, Ca, Nd, Nb, Ta, Sb, Bi, Si, Cr, Fe, Sc, Sr, and Pb. PZT-based material, because the smaller compliance than the relaxor materials, at 150 ≦ │d ₃₃ │, further preferably ranges from │d ₃₃ │ ≦ 300. Further, 150 ≦ | d ₃₁ | is more preferable than the case of using the piezoelectric actuator using the transverse vibration mode.

The relaxor-based piezoelectric material described in this specification is a group of ferroelectric materials generally referred to as having a broad shape with a temperature dependence of dielectric constant. For example, (Pb (Mn, Nb) O ₃ ) _1-x − (PbTiO ₃ ) _x (PMN-PT) [0 ≦ x <1], (Pb (Zn, Nb) O ₃ ) _1-x − (PbTiO ₃ ) _x (PZN-PT) [0 ≦ x <1], (Pb (Ni, Nb) O ₃ ) _1-x − (PbTiO ₃ ) _x (PNN-PT) [0 ≦ x <1], (P (In, Nb) O ₃ ) _1-x − (PbTiO ₃ ) _x (PIN-PT) [0 ≦ x <1], (P (Sc, Nb) O ₃ ) _1-x − (PbTiO ₃ ) _x ( PSN-PT) [0 ≦ x <1], (P (Yb, Nb) O ₃ ) _1-x- (PbTiO ₃ ) _x (PYN-PT) [0 ≦ x <1], and the like. Since relaxer materials have large compliance, it is preferable to have a range of | d ₃₃ | ≦ 150. Further, 150 ≦ | d ₃₁ | is more preferable than the case of using the piezoelectric actuator using the transverse vibration mode.

  As described above, the PZT-based and relaxor-based piezoelectric materials have been described with specific examples, but the PZT-based and relaxor-based piezoelectric materials according to the present embodiment are not limited to these specific examples.

[Uniaxial crystal / single crystal]
The uniaxially oriented crystal described in this specification refers to a crystal having a single crystal orientation in the film thickness direction, and the crystal in-plane orientation is not particularly limited. FIG. 3 shows a pattern obtained when the pole of an {110} asymmetric surface is measured by X-ray diffraction. FIG. 3A shows the case of a uniaxially oriented crystal having a <100> PZT perovskite structure. FIG. 3B shows the case of a <100> single crystal having a PZT perovskite structure.

  For example, a <100> uniaxially oriented crystal is a film composed of crystals having a film thickness direction only in the <100> orientation. Whether the piezoelectric film is a uniaxial crystal can be confirmed using X-ray diffraction. For example, in the case of a <100> uniaxially oriented crystal having a PZT perovskite type structure, peaks caused by the piezoelectric film in 2θ / θ measurement of X-ray diffraction are (L00) planes such as {100}, {200} (L = Only peaks of 1, 2, 3,..., N: n is an integer) are detected. In addition, when the pole measurement of the {110} asymmetric surface is performed, a ring-shaped pattern is obtained at the same radial position representing an inclination of about 45 ° from the center as shown in FIG.

  The single crystal described in this specification refers to a crystal having a single crystal orientation in the film thickness direction and the in-plane direction. For example, a <100> single crystal is a film composed of crystals having a film thickness direction only in the <100> orientation and one in-plane direction having only the <110> orientation. Whether the piezoelectric film is a uniaxial crystal can be confirmed using X-ray diffraction. For example, in the case of a <100> single crystal having a PZT perovskite structure, the peak due to the piezoelectric film in the 2θ / θ measurement of X-ray diffraction is the (L00) plane (L = 1, {100}, {200}, etc.) 2, 3... N: n is an integer) only. In addition, when measuring the extreme point of the {110} asymmetric surface, a spot-like pattern that is symmetric four times every 90 ° is obtained at the same radial position representing an inclination of about 45 ° from the center as shown in FIG. It is done.

  Further, for example, in a PZT perovskite type structure with <100> orientation, when measuring a pole of a {110} asymmetric surface, an 8-fold or 12-fold symmetric pattern is formed at the same radial position representing an inclination of about 45 ° from the center. Some crystals are obtained. Alternatively, some crystals have an oval pattern instead of a spot. These crystals are also crystals having an intermediate symmetry between the single crystal of the present embodiment and the uniaxially oriented crystal, and thus are regarded as a single crystal and a uniaxially oriented crystal in a broad sense. Similarly, for example, when multiple crystal phases such as monoclinic and tetragonal, monoclinic and rhombohedral, tetragonal and rhombohedral, etc. are mixed (mixed phase), or crystals due to twins are mixed When there is a dislocation or a defect, it is regarded as a single crystal and a uniaxially oriented crystal in a broad sense.

[electrode]
In the piezoelectric element of the present embodiment, a pair of electrodes (an upper electrode and a lower electrode) are arranged so as to be in contact with the piezoelectric body.

As the electrode material, any material may be used as long as the lower electrode and the upper electrode have conductivity that can effectively apply an electric field to the piezoelectric body. For example, metal materials such as Au, Pt, Ir, Al, Ti, and Ta, and metal oxide materials such as IrO ₂ and RuO ₂ can be used. Furthermore, the lower electrode and the upper electrode may have a multilayer structure. Preferably, at least one of the lower electrode and the upper electrode is configured to include a conductive oxide layer. In particular, the lower electrode preferably has a conductive oxide layer. That is, when controlling the crystal state of the piezoelectric body of the piezoelectric element, specifically, when controlling the crystal state to be uniaxially oriented or single crystal, the following can be said. That is, when the piezoelectric element is formed in the order of the diaphragm, lower electrode, piezoelectric body, and upper electrode, or in the order of the diaphragm, buffer layer, lower electrode, piezoelectric body, and upper electrode, the crystalline state of the piezoelectric body In order to control this, the crystal structure of the lower electrode becomes important.

At this time, a conductive oxide material can be suitably used as the lower electrode. Examples thereof include SrTiO ₃ , SrRuO ₃ , BaPbO ₃ , LaNiO ₃ , and Pb ₂ Ir ₂ O ₇ doped with La or Nb.

  More preferably, the lower electrode has two or more conductive oxide layers. This is the same structure as the case where the buffer layer is made of a conductive oxide material, and it becomes possible to control the crystal structure of the piezoelectric body in which the control of the crystal structure greatly affects the characteristics in a better state. .

  Further, in the case of forming the upper electrode, the piezoelectric body, and the lower electrode in this order using the transfer method, the crystal structure of the upper electrode is important, and the above-described metal oxide of the lower electrode can be preferably used.

  In addition, the thickness of the lower electrode and the upper electrode is determined as the minimum thickness required to have conductivity necessary for effectively applying an electric field to the piezoelectric body as an electrode. This can be determined from the conductivity of the electrode material, the dimension of the piezoelectric element, and the like.

  The maximum thickness is not particularly limited because the lower electrode can also serve as a diaphragm function of the bending mode type piezoelectric element. However, the upper electrode can only be a load in the transverse vibration mode, so that it is possible. Thin is preferred.

  When the lower electrode does not function as a diaphragm, both the lower electrode and the upper electrode have an optimum thickness in the range of 10 nm to 1 μm.

[Vibration plate]
In the piezoelectric element of the present embodiment, a diaphragm can be further provided on one of the electrodes (lower electrode). The diaphragm is an essential component as a bending mode type piezoelectric element for effectively taking out the displacement of the transverse vibration mode of the piezoelectric body according to the present embodiment.

As the main material used for the diaphragm, an oxide such as ZrO ₂ , BaTiO ₃ , MgO, SrTiO ₃ , MgAl ₂ O ₄ and / or Si doped with rare earth elements including Sc and Y can be used. Si may contain a dopant element such as a B element. A diaphragm mainly composed of these materials has a specific and controlled crystal structure. When the crystal structure of <100>, <110>, or <111> is oriented with an intensity of 80% or more, the polarization axis direction of the piezoelectric body is aligned with the driving electric field to be applied, and is used as a piezoelectric actuator. However, a stable displacement can be obtained, which is preferable. More preferably, it is 99% to 100%. Here, “99%” means that an orientation different from the main orientation of 1% in XRD strength exists.

  More preferred is <100> uniaxial orientation or single crystal. This is preferable because the direction of the polarization axis of the piezoelectric body matches the direction of the drive electric field to be applied, so that stable and large displacement can be obtained.

  In addition, the surface of the diaphragm that comes into contact with various materials during use, such as a diaphragm of a liquid ejection device that ejects ink for image formation or the like, has an oxide layer that is chemically bonded and stable. Is preferred.

[Buffer layer]
When controlling the crystal state of the piezoelectric body of the piezoelectric element, specifically, when controlling the crystal state to be uniaxially oriented or single crystal, the piezoelectric body is uniaxially orientated between the diaphragm and the lower electrode. A buffer layer may be formed for the purpose of controlling and synthesizing a single crystal in a crystalline state. The buffer layer may be a plurality of layers.

  As the material for the buffer layer, a material whose lattice constant matches the lattice constant of the substrate within a range of 8% or less is preferable. The buffer layer is preferably an oxide that can be formed by sputtering, MO-CVD, or laser ablation, and preferably has a cubic or pseudo-cubic crystal structure with a crystal constant of 3.6 to 6.0 mm. .

Specific configurations include, for example, 10% Y ₂ O ₃ —ZrO ₂ (100) / Si (100), 10% Y ₂ O ₃ —ZrO ₂ (111) / Si (111), SrTiO ₃ (100) / MgO (100), MgAl ₂ O ₄ (100) / MgO (100), BaTiO ₃ (001) / MgO (100) and the like. Here, the lattice constant of 10% Y ₂ O ₃ -ZrO ₂ is 5.16Å, SrTiO ₃ is 3.91A, MgO is 4.21Å, MgAl ₂ O ₄ is 4.04Å, BaTiO ₃ is 3.99A, Si is a 5.43Å . When the lattice constant consistency is calculated, for example, 10% Y ₂ O ₃ —ZrO ₂ (111) / Si (111) is taken as an example. _{10% Y 2 O 3 -ZrO 2} (111) is 5.16 × √2 = 7.30Å, with Si (111) is 5.43 × √2 = 7.68Å, differences in consistency becomes 4.9%, it is found that a good .

[Piezoelectric synthesis and deposition method]
Suitable methods for synthesizing and forming the piezoelectric body of the present embodiment include sol-gel method, hydrothermal synthesis method, sputtering method, MBE method, PLD method, CVD method, MOCVD method, etc. A method is mentioned. These thin film forming methods are synthesis / film forming methods suitable for forming a film thickness on the order of 10 nm to 10 μm. Among these, the MOCVD method is particularly preferable.

  Hereinafter, a piezoelectric material synthesizing / film forming method of the piezoelectric element according to the present embodiment will be described with reference to the drawings.

  FIG. 4 is a schematic diagram showing the structure and mechanism of the MOCVD apparatus. Reference numerals 401, 402, and 403 denote starting material storages that can store starting materials of materials to be synthesized and formed, and can appropriately adjust the partial pressure of the starting materials optimized using an inert carrier gas. A heating device (not shown) for adjusting the partial pressure of the raw material is added to each.

  When the starting material is liquid, as shown at 401 and 402, an inert carrier gas is blown into the starting material, and bubbling is performed to efficiently produce a starting material gas / inert carrier gas mixed gas.

  When the starting material is solid, the starting material gas / inert gas mixed gas is efficiently produced by directly spraying the inert carrier gas on the surface of the starting material.

  The inert carrier gas / starting material mixed gas whose partial pressure and flow rate of each starting material are adjusted in accordance with the target composition / film forming material composition is mixed through the starting material mixed gas supply path 404. Then, the starting raw material mixed gas is sprayed from the nozzle 406 in the reaction chamber 405 to the substrate disposed in the substrate folder 407. When an oxide film is formed, the raw material oxygen gas can be supplied from the oxygen gas supply path 408 to the nozzle 406. At this time, it is mixed with an inert carrier gas before being supplied to the nozzle 406, and the oxygen supply pressure during synthesis and film formation can be adjusted by adjusting the oxygen partial pressure in addition to the supply flow rate. .

  An inert carrier gas / starting raw material mixed gas can also be supplied intermittently.

  Further, a heating device (not shown) is added to the substrate folder 407 so that the film forming temperature can be adjusted, and a rotation mechanism is added to perform uniform film formation.

  The decompression device 409 is connected to the reaction chamber 405 so that the pressure in the reaction chamber 405 during film formation can be adjusted.

  In the MOCVD method, for example, a starting material for forming a PZT-based material can be a known starting material that can be used for forming the PZT-based material by the MOCVD method, and is not particularly limited. That is, any vaporizable organometallic compound containing a metal constituting the PZT-based material may be used. In general, an alkyl metal compound, an alkoxy metal compound, an alkyl alkoxy metal compound, a β-diketone compound, a cyclopentadienyl compound, a halide, or the like is used.

For example, when ((CH ₃ ) ₃ CCO) ₂ CH— is represented by thd,
Pb (C ₂ H ₅ ) ₄ , Pb (thd) ₂ , (C ₂ H ₅ ) ₃ PbOCH ₂ C (CH ₃ ) ₃ , Pb (C ₂ H ₅ ) ₃ (t-OC ₄ H ₉₎ ), Pb (CH ₃ ) ₄ , PbCl ₄ , Pb (n-C ₃ H ₇ ) ₄ , Pb (i-C ₃ H ₇ ) ₄ , Pb (C ₆ H ₅ ) ₄ , PbCl _{2 and the} like;
Of Zr raw _{material, Zr (t-OC 4 H} 9) 4, Zr (i-C 3 H 7) 4, Zr (thd) 4, ZrCl 4, Zr (C 5 H 5) 2 Cl 2, Zr (OCH 3 ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (n-OC ₅ H ₁₁ ) ₄ , Zr (C ₂ H ₆ O ₂ ) _{4 and the} like;
As the Ti _{source, Ti (i-OC 3 H} 7) 4, Ti (thd) 2 (i-OC 3 H 7) 2, Ti (OC 2 H 5) 4, TiCl 4, Ti (OCH 3) 4, Ti (OCH ₉ ) ₄ , Ti (OC ₅ H ₁₁ ) _{4 and the} like;
Can be mentioned.

In PZT, a part of Pb is replaced with La or the like. In this case, La (thd) ₃ , La (C ₂ H ₆ O ₂ ) ₄ , LaCl ₃ or the like is used as the La raw material. be able to.

As _{the, Mg [6-C 2 H} 5 -2,2- (CH 3) 2 -C 10 H 15 O 2] 2, Mg (thd) 2 such as Mg raw material; the Nb material, Nb (C _{2 H 5) 5, NbC 3} H 7 (C 2 H 5) 4, Nb (O-iC 3 H 7) 5 and the like; a.

  Many of these raw materials are not only toxic but also solid or liquid at room temperature and have a low vapor pressure. Therefore, it is necessary to increase the vapor pressure by heating.

  In order to uniformly introduce the starting raw material mixed gas into the reaction chamber, it is preferable to mix the raw material gases before introduction. In addition, it is preferable to control the temperature of the starting material supply path so that an oxidation reaction that inhibits single crystal film formation does not proceed in the pipe. For example, in the PZT system, the heating temperature can be in the range of 30 ° C. to 250 ° C., depending on the raw material species.

  The film can be formed without rotating the substrate. However, when the substrate is rotated, it is preferable to adjust in the range of 0.01 rpm to 100 rpm.

Specifically, for example, Ar, N ₂ , He, or the like can be used as the inert carrier gas. Moreover, these mixed systems may be sufficient. Flow rate of inert carrier gas is adjusted within a range of 10 cm ³ / min to 1000 cm ³ / min.

  Although the bubbling time before film formation of the liquid raw material depends on the structure of the apparatus, it is preferably 5 minutes to 2 hours, more preferably 10 minutes to 1 hour. If film formation is started without this time, the composition control of the film formed in the initial stage may be inferior.

As the oxidizing gas, oxygen gas or oxygen / inert gas mixed gas is used. This flow rate can be adjusted from 10 cm ³ / min to 5000 cm ³ / min.

  By controlling the flow rate of each gas, the total pressure in the reaction chamber can be formed at 0.05 to 100 torr.

  Thereby, although the film forming speed is not limited, for example, it is within a preferable range of about 0.1 μm / hr to 5 μm / hr, and stable film formation can be performed.

[Liquid discharge head]
Next, an outline of a liquid discharge head to which the piezoelectric element of the present embodiment is applied will be described with reference to FIG. FIG. 5 is a schematic diagram showing an example of the structure of an ink jet head that is a liquid discharge head, in which 501 is an ejection port, 502 is an individual liquid chamber, 503 is a communication hole that connects the individual liquid chamber 502 and the ejection port 501, and 504 is A common liquid chamber 506 is a throttle unit that restricts the ink flow between the individual liquid chamber 502 and the common liquid chamber 504. Reference numeral 505 denotes a diaphragm, 507 denotes a lower electrode, 508 denotes a piezoelectric body, and 509 denotes an upper electrode. These shapes are not particularly limited by the drawings, but are examples when the piezoelectric element of the present embodiment is applied to an inkjet head. Note that the piezoelectric element in this example is a portion including a portion where the piezoelectric body 508 is sandwiched between the lower electrode 507 and the upper electrode 509 and a diaphragm 505 provided on the lower electrode 507.

  The portion related to the piezoelectric body 508 of this embodiment will be described in more detail with reference to FIG. 6 is a cross-sectional view in the width direction of a portion including the piezoelectric body 508 of FIG. Reference numeral 508 denotes a piezoelectric body, reference numeral 505 denotes a diaphragm, reference numeral 507 denotes a lower electrode, and reference numeral 509 denotes an upper electrode. An intermediate layer 510 having a function such as a buffer layer for controlling crystallinity may be provided between the diaphragm 505 and the lower electrode 507, and the intermediate layer 510 has a plurality of layer structures. It doesn't matter. Further, the lower electrode 507 and the upper electrode 509 may have a plurality of layer structures having a function such as a layer for improving adhesion. Although the cross-sectional shape of the piezoelectric body 508 is displayed as a rectangle, the shape is not limited to this.

  The lower electrode 507 is drawn to a portion where the piezoelectric body 508 does not exist, and the upper electrode 509 is drawn to the side (not shown) opposite to the lower electrode 507 and connected to a driving power source. 5 and 6 show a state in which the lower electrode is patterned, it may exist also in a portion where there is no piezoelectric body.

  In the inkjet head of this embodiment, it is preferable that the thickness of the vibration plate 505 is 1.0 to 10 μm because it substantially matches the order of the thickness of the piezoelectric body to be used, and the displacement in the transverse vibration mode can be taken out effectively. More preferably, it is 1.0-6.0 micrometers. When there is a buffer layer, this thickness includes the thickness of the buffer layer. The film thicknesses of the lower electrode 507 and the upper electrode 509 are preferably 0.05 to 0.4 μm, more preferably 0.08 to 0.2 μm.

  FIG. 7 is a diagram showing the structure of one unit of the inkjet head. The width Wa of the individual liquid chamber 502 is preferably 30 to 180 μm. The length Wb of the individual liquid chamber 502 is preferably 0.3 to 6.0 mm, although it depends on the discharge droplet amount. The shape of the discharge port 501 is preferably circular, and the diameter is preferably 7 to 30 μm. It is preferable to have a tapered shape expanded in the direction of the communication hole 503. The length of the communication hole 503 is preferably 0.05 mm to 0.5 mm. If the length is longer than this, the droplet discharge speed may be reduced. On the other hand, if it is less than this, there is a fear that the variation in the ejection speed of the droplets ejected from each ejection port becomes large.

[Liquid ejection device]
A liquid discharge apparatus using the liquid discharge head of this embodiment will be described.

  FIG. 8 shows a schematic diagram of an ink jet recording apparatus using an ink jet head to which the piezoelectric element of the present embodiment can be suitably applied. Further, FIG. 9 shows a schematic diagram of the operation mechanism part with the exterior of the ink jet recording apparatus of FIG. 8 removed.

  An automatic feeding unit 801 for automatically feeding a recording sheet as a recording medium into the apparatus main body, and a recording sheet sent from the automatic feeding unit 801 are guided to a predetermined recording position, and from the recording position to the discharge port 802. And a conveyance unit 803 for guiding the recording paper. In addition, the recording unit includes a recording unit that performs recording on the recording sheet conveyed to the recording position, and a recovery unit 804 that performs recovery processing on the recording unit. The ink jet head according to this embodiment is disposed on a carriage 805 and used.

  In the present embodiment, an example of a printer is shown, but the present embodiment may be used for a fax machine, a multifunction machine, a copier, or an industrial discharge apparatus.

[Example 1]
Examples of the present embodiment will be described in detail with reference to the drawings.

  FIG. 10 is a cross-sectional view illustrating a manufacturing process for producing an ink jet head using the piezoelectric element of the present embodiment.

1001 is a SOI substrate has a structure of the Si (100) 200 [mu] m the SiO ₂ layer 1003,3μm substrate 1002,0.3μm of Si (100) layer 1004 (10-1).

Reactive sputter deposition of stabilized zirconia (10% Y ₂ O ₃ —ZrO ₂ : YSZ) on an SOI substrate 1001 in an Ar / O ₂ atmosphere at a substrate temperature of 800 ° C. was performed, and a buffer layer of 0.1 μm was formed. A (100) YSZ epitaxial film 1005 was formed. After that, LaNiO ₃ : LNO was sputter-deposited in an Ar / O ₂ atmosphere at a substrate temperature of 500 ° C. to form a 0.1 μm (100) LNO epitaxial film 1006. Next, as a lower electrode, SrRuO ₃ : SRO was formed by sputtering in an Ar / O ₂ atmosphere at a substrate temperature of 600 ° C. to form a 0.2 μm (100) SRO epitaxial film 1007 (10-2). At the same time, YSZ, LNO, and SRO were similarly formed on a Si (100) substrate having a thickness of 625 μm.

Next, 3 μm of (Pb (Mn _0.33 , Nb _0.67 ) O ₃ ) _0.67- (PbTiO ₃ ) _0.33 (PMN-PT) was formed as a piezoelectric body 1008 on the substrate by MOCVD (10-3). The film forming method will be described in detail below.

First, as a starting material,
Pb (thd) ₂ : bis (hexamethylacetylacetonate) lead
Mg [6-C ₂ H ₅ -2,2- (CH ₃ ) ₂ -C ₁₀ H ₁₅ O ₂ ] ₂ : bis [6-ethyl-2,2-dimethyl-3,5-decanedionate] magnesium
_{NbC 3 H 7 (C 2 H} 5) 4: propyl tetraethyl niobium _{Ti (C 3 H 7 O)} 4: prepared titanium tetraisopropoxide, carried piezoelectric film formation using the MOCVD apparatus shown in FIG. 11 It was. The basic configuration is the same as that of the MOCVD apparatus shown in FIG. 4, and each requirement is as follows.

Each starting material is heated to form a mixed gas with nitrogen N ₂ gas used as an inert carrier gas, and the molar ratio of each raw material gas in the inert carrier gas / starting material mixed gas supply path is determined as a target film. Adjusted to the composition. At the same time, the supply amount of oxygen O ₂ was 15 [cm ³ / min], and the Pb raw material and the O ₂ raw material were excessively supplied relative to the film composition after film formation.

  In this embodiment, a pulse MOCVD film forming method in which raw material supply is intermittently used is used.

In the pulse MOCVD method, a time t _{1 in} which a gas obtained by mixing an inert carrier gas / starting material mixed gas and oxygen gas is sprayed from a nozzle onto a film forming substrate to form a film, and an inert carrier gas / starting material mixed gas is supplied. the stop by setting the time t ₂ alternately conduct synthesis and deposition. In this embodiment, a gas obtained by mixing an inert carrier gas / starting raw material mixed gas and oxygen gas is sprayed from a nozzle onto a film-forming substrate from a nozzle, and two levels t ₁₁ and t ₂ are respectively provided for times t ₁ and t _{2. 12} and set a t _21, t _22. FIG. 12 shows a time sequence when t ₁₁ , t ₁₂ and t ₂₁ , t ₂₂ are set. The time sequence shown in FIG. 12 was employed to perform synthesis and film formation.

The respective times were t ₁₁ = 10 [sec], t ₁₂ = 25 [sec], t ₂₁ = 15 [sec], and t ₂₂ = 20 [sec].

At times t ₁₁ and t ₁₂ during which the raw material was supplied, the reaction chamber pressure was 8.5 [torr], and the oxygen partial pressure at that time was 6.0 [torr].

  The film formation substrate (SOI and Si) was placed in a substrate folder, the film formation substrate temperature was adjusted to 650 ° C., and the substrate folder was rotated at 2.0 rpm for synthesis and film formation.

  When the crystal structure analysis of the formed piezoelectric body 1008 (PMN-PT) was performed, both the PMN-PT on the SOI substrate and the PMN-PT on the Si substrate were epitaxially grown on the substrate (100) single crystal. It was confirmed. The crystal structure analysis was performed using a high-resolution X-ray diffractometer (XRD, PANalytical X'pert-MRD) having four axes.

Further, when the composition analysis of the formed piezoelectric body 1008 (PMN-PT) was performed, the PMN-PT on the SOI substrate and the PMN-PT on the Si substrate were both (Pb (Mn _0.33 , Nb _0.67 ) O _3. ) _0.67- (PbTiO ₃ ) _0.33 was confirmed. For the composition analysis, a wavelength dispersive X-ray fluorescence analyzer (XRF, PANalytical PW2404) was used.

  Next, an inkjet head was manufactured using an SOI substrate on which PMN-PT formed as the piezoelectric body 1008 was formed. The manufacturing process will be described below.

  As an upper electrode 1009 patterned to 0.15 mm × 5 mm corresponding to each individual liquid chamber of the inkjet head on the piezoelectric body 1008 formed on the SOI substrate 1001, Au is formed by DC sputtering with a thickness of 200 nm. A film was formed (10-4).

  Next, the piezoelectric body 1008 was removed by a dry etching process using the patterned upper electrode 1009 as a mask (10-5).

  Next, the Si substrate 1002 portion of the SOI substrate 1001 was etched in two stages by a dry etching process to mold the individual liquid chamber 1011, the throttle portion 1012, and the common liquid chamber 1013 (10-6).

  Next, a nozzle plate 1015 having a discharge port 1014 of 30 μmφ was bonded to the SOI substrate 1001 using an organic adhesive to produce an ink jet head (10-7).

The performance of the inkjet head was evaluated by measuring the amount of ink discharged at 10 kHz drive and the amount of change between the ink discharge immediately after the start of discharge and the ink discharge after 10 ¹⁰ discharge endurance tests. When the difference in discharge amount is less than 3% with respect to the initial value, ◎, 3% or more and less than 5%, ◯, 5% or more as x.

  The results are listed in Table 1.

Next, a method for producing samples for evaluating the piezoelectric constants d ₃₃ and d _{31 of} the synthesized and formed piezoelectric material will be described below.

The following electrodes were formed on a PMN-PT / SRO / LNO / YSZ / Si (100) substrate on which PMN-PT was formed as a piezoelectric body simultaneously with the SOI substrate for forming the inkjet head. That is, a 100 μmφ Au electrode as a d ₃₃ measurement electrode and a 12 mm × 3 mm rectangular Au electrode as a d ₃₁ measurement electrode were formed on the PMN-PT by DC sputtering with a thickness of 100 nm. At this time, the 12 mm × 3 mm rectangular Au electrode of the d ₃₁ measuring electrode has (010), (001) plane, (010) plane (each side of the rectangle is perpendicular to the (100) plane of the Si substrate (100)). The arrangement was parallel to the (01 bar 0) plane and the (001 bar) plane.

FIG. 13 shows a d ₃₁ measurement sample. (13-1) shows a side view of the layer structure after cutting, and (13-2) shows a top view. As described above, the d ₃₁ measurement sample having the shape shown in FIG. 13 was cut by a dicer as the d ₃₁ measurement sample. In FIG. 13, (13-1) is a side view showing the layer structure of the d ₃₁ measurement sample after cutting, and (13-2) is a top view showing the shape of the sample.

A method for determining the piezoelectric constant d ₃₃ will be described in detail below.

[d ₃₃ measurement method]
d ₃₃ determinations were made by using a combination of a general method in which scanning probe microscope (SPM = Scanning Probe Microscope) a ferroelectric tester to measure the electric-field-induced strain of the thin-film piezoelectric member. The scanning probe microscope was SPI-3800 (trade name, manufactured by Seiko Instruments Inc.), and the ferroelectric tester was FCE-1 (trade name, manufactured by Toyo Technica).

FIG. 14 shows a schematic diagram of a d ₃₃ measuring apparatus in which a scanning probe microscope and a ferroelectric tester are combined.

  In FIG. 14, the SPM includes a sample stage 1401, a sample stage height adjustment actuator 1402, a cantilever 1403, a cantilever displacement detector 1404, and a control device 1405. The cantilever 1403 is scanned (scanned) in the X-axis and Y-axis directions (sample plane direction), and the movement of the cantilever 1403 in the Z-axis direction (height direction) at that time is detected by the cantilever displacement detector 1404. By doing so, for example, it is possible to know minute irregularities on the sample surface. Further, a feedback Z-axis control signal is determined by the control unit 1405 from the movement of the cantilever 1403 in the Z-axis direction detected by the cantilever displacement detector 1404. A configuration in which the feedback Z-axis control signal that makes the position of the cantilever 1403 in the Z-axis direction constant can be sent from the terminal 1405-b to the signal sample stage height adjustment actuator 1402 and the position of the cantilever 1403 in the Z-axis direction can be made constant. It has become.

  The ferroelectric tester 1406 is configured to apply a voltage to the sample between the terminals 1406-a and 1406-b and monitor the amount of current and the amount of charge at that time. Further, the feedback Z-axis control signal of the SPM is taken into the terminal 1406-c.

The SPM sample stage 1401 is in an electrically floating state, is connected to the side terminal 1406-a that supplies the voltage of the voltage application terminal of the ferroelectric tester 1406, and is connected to the lower electrode of the d ₃₃ measurement sample 1411. Yes. The other Gnd terminal 1406-b is connected to the SPM cantilever 1403 to conductive treatment, contact the upper electrode of the d ₃₃ measurement sample 1411, the d ₃₃ measurement sample 1411, may be added voltage.

In d ₃₃ measurement, the measurement time of the cantilever 1403, X-axis, Y-axis direction of the scan (scanning) is not performed, X-axis, the measurement is carried out in the stationary state in the Y-axis direction.

By measuring the displacement with respect to the input voltage, d ₃₃ of the piezoelectric body can be determined.

In the determination of d _{33 in} this embodiment, an electric field of 0 to 150 [kV / cm] (a voltage of 0 to 45 V is applied to a piezoelectric film thickness of 3 μm) is applied to the piezoelectric body as an input signal voltage to the sample. I gave a triangular wave of 10Hz. For the polarity, the polarity that maximizes the displacement in the same electric field was selected.

  The sample expands and contracts with respect to the input signal voltage. SPM read it as a change in the Z-axis direction.

Using the above means show the d ₃₃ was measured and determined in Table 1.

Next, a method for determining the piezoelectric constant d ₃₁ will be described in detail below.

[d ₃₁ measurement method]
The d ₃₁ determination was performed using a unimorph type cantilever method.

FIG. 15 is a diagram for explaining the d ₃₁ measurement, (15-1) is a schematic diagram of a unimorph type cantilever displacement measuring device, and (15-2) is a schematic diagram showing a basic sample layer structure. FIG.

  A piezoelectric element 1501 composed of a lower electrode 1501-b, a piezoelectric body 1501-c and an upper electrode 1501-d on a substrate 1501-a in this order has a configuration of a unimorph type cantilever in which one side is fixed by a clamp jig 1502. It has become. The upper part 1502-a of the clamp jig 1502 is made of a conductive material, is in electrical contact with the lower electrode 1501-b of the piezoelectric element 1501, and is one of output terminals (not shown) of the AC power supply 1503. ) Is connected to the electric cable 1504-a. The other output terminal (not shown) of the AC power supply 1503 is connected to the upper electrode 1501-d of the piezoelectric element 1501 through the electric cable 1504-b, and an AC voltage is applied to the piezoelectric body 1501-c of the piezoelectric element 1501. It can be configured.

  The piezoelectric body 1501-c expands and contracts due to the electric field supplied by the AC power supply 1503. Along with this, the substrate 1501-a is distorted, and the piezoelectric element 1501 vibrates up and down with the end portion fixed by the clamp jig 1502 as a fulcrum. At this time, the vibration of the unclamped end of the piezoelectric element 1501 is monitored by a laser Doppler velocimeter (LDV) 1505 so that the displacement amount of the unimorph type cantilever with respect to the input electric field can be measured.

  At this time, the displacement amount of the unimorph type cantilever with respect to the input voltage V is approximately in the relationship of Formula 1 (see Non-Patent Document 2).

Formula 1 does not include physical property value terms such as the lower electrode layer, the upper electrode layer, and other buffer layers. However, when the thickness is sufficiently small with respect to the substrate thickness h ^s , these layers are not included. The physical property values and film thicknesses of these are negligible, and Equation 1 is an approximate equation sufficient for practical use.

From Equation 1, d ₃₁ of the piezoelectric body can be determined by measuring the amount of displacement of the unimorph type cantilever with respect to the input electric field.

In the determination of d _{31 in} this embodiment, an electric field of 0 to 150 [kV / cm] (a voltage of 0 to 45 V is applied to a piezoelectric film thickness of 3 μm) is applied to the piezoelectric body as an input signal voltage to the sample. Like gave a 500Hz sin wave. In the same field for that polarity, displacement select the polarity as the maximum which is consistent with the polarity at the time of d ₃₃ determined. The reason for adopting the sin wave as the input signal voltage is that the displacement of the cantilever tip δ eliminates the inertial term of the oscillating motion because the mass of the cantilever is large.

D ₃₁ was determined by measuring the displacement δ at the tip of the cantilever with respect to the input signal voltage.

The physical properties used in Equation 1 are S ₁₁ ^S = 7.7 × 10 ⁻¹² [m ² / N]
S ₁₁ ^P = 70.2 × 10 ⁻¹² [m ² / N]
It was. For S ₁₁ ^P , the value described in Non-Patent Document 3 is used.

  The results are shown in Table 1.

[Example 2]
As the piezoelectric body, a piezoelectric body having a composition of (Pb (Mn _0.33 , Nb _0.67 ) O ₃ ) _0.70 − (PbTiO ₃ ) _0.30 was formed to a thickness of 2.8 μm. Others were made in the same manner as in Example 1, an ink jet head and a sample for determining piezoelectric constants d ₃₃ and d ₃₁ were prepared, and the performance evaluation and piezoelectric constant were determined. The results are shown in Table 1.

The physical properties used in Equation 1 are S ₁₁ ^S = 7.7 × 10 ⁻¹² [m ² / N]
S ₁₁ ^P = 51.2 × 10 ^-12 [m ² / N]
It was. For S ₁₁ ^P , the value described in Non-Patent Document 3 is used.

[Example 3]
Using a YSZ (10% Y ₂ O ₃ —ZrO ₂ : YSZ) oxide target on the same SOI and Si substrate as described in Example 1, sputtering film formation was performed at an substrate temperature of 800 ° C. in an Ar / O ₂ atmosphere. Then, a 0.1 μm YSZ (100) uniaxial alignment film was formed as a buffer layer. Next, SRO was deposited as a lower electrode in an Ar / O ₂ atmosphere at a substrate temperature of 600 ° C. to form a 0.2 μm SRO (100) uniaxially oriented film.

Next, a film of (Pb (Mn _0.33 , Nb _0.67 ) O ₃ ) _0.67- (PbTiO ₃ ) _0.33 (PMN-PT) was formed to a thickness of 3.0 μm as a piezoelectric body.

At this time, a gas t which is a mixture of an inert carrier gas / starting raw material mixed gas and oxygen gas is sprayed from a nozzle onto a film forming substrate from the nozzles at times t ₁₁ and t _12, and the inert carrier gas / starting raw material mixed gas Times t ₂₁ and t ₂₂ for stopping the supply were set as follows.
t ₁₁ = 10 [sec], t ₁₂ = 25 [sec], t ₂₁ = 10 [sec], t ₂₂ = 25 [sec].

  When the crystal structure analysis of the deposited piezoelectric material PMN-PT was performed, it was confirmed that both PMN-PT on the SOI substrate and PMN-PT on the Si substrate are (100) uniaxially oriented films. .

Except for the above, an ink jet head and a sample for determining the piezoelectric constants d ₃₃ and d ₃₁ were prepared in the same manner as in Example 1, and the performance evaluation and the piezoelectric constant were determined. The results are shown in Table 1.

The physical properties used in Equation 1 are S ₁₁ ^S = 7.7 × 10 ⁻¹² [m ² / N]
S ₁₁ ^P = 70.2 × 10 ⁻¹² [m ² / N]
It was. For S ₁₁ ^P , the value described in Non-Patent Document 3 is used.

[Example 4]
The same film-forming substrate (SRO / YSZ / SOI and SRO / YSZ / Si) as in Example 3 was prepared.

In the MOCVD film forming method for forming a piezoelectric body, Pb (thd) _{2 is used} as a starting material.
Zr (Ot-C ₄ H ₉ ) ₄
Ti (O-i-C ₃ H ₇ ) ₄
And Pb (Zr _0.5 , Ti _0.5 ) O ₃ (PZT) was formed to a thickness of 3.2 μm.

At this time, this time, and the time t ₁₁ and t ₁₂ for forming blown from the nozzle gas that is a mixture of inert carrier gas starting material mixed gas and the oxygen gas to the deposition substrate, inactive carrier gas and starting materials Times t ₂₁ and t ₂₂ for stopping the supply of the mixed gas were set as follows.
t ₁₁ = 10 [sec], t ₁₂ = 25 [sec], t ₂₁ = 15 [sec], t ₂₂ = 20 [sec].

  When the crystal structure analysis of the formed piezoelectric material PZT was performed, it was confirmed that both PZT on the SOI substrate and PZT on the Si substrate were (100) uniaxially oriented films.

Except for the above, an ink jet head and a sample for determining the piezoelectric constants d ₃₃ and d ₃₁ were prepared in the same manner as in Example 1, and the performance evaluation and the piezoelectric constant were determined. The results are shown in Table 1.

The physical properties used in Equation 1 are S ₁₁ ^S = 7.7 × 10 ⁻¹² [m ² / N]
S ₁₁ ^P = 12.4 × 10 ⁻¹² [m ² / N]
It was. For S ₁₁ ^P , the value described in Non-Patent Document 1 is used.

[Comparative Example 1]
As a film formation substrate, Ti and Pt were formed by DC sputtering on the SOI substrate and Si substrate described in Example 1, and Pt (150 nm) / Ti (5 nm) / SOI and Pt (150 nm) / Ti ( 5 nm) / Si was prepared.

The piezoelectric film was formed by preparing a metal oxide ceramic target Pb _1.1 (Zr _0.5 , Ti _0.5 ) O ₃ . Specifically, after forming a film in an Ar / O ₂ atmosphere at a substrate temperature of 30 ° C., a baking process is performed at 700 ° C. for 2 hours to form a Pb (Zr _0.5 , Ti _0.5 ) O ₃ (PZT) polycrystalline film. A 0 μm film was formed.

  When the crystal structure analysis of the formed piezoelectric material PZT was performed, it was confirmed that both PZT on the SOI substrate and PZT on the Si substrate were non-oriented polycrystalline films.

Except for the above, an ink jet head and a sample for determining the piezoelectric constants d ₃₃ and d ₃₁ were prepared in the same manner as in Example 1, and the performance evaluation and the piezoelectric constant were determined. The results are shown in Table 1.

The physical properties used in Equation 1 are S ₁₁ ^S = 7.7 × 10 ⁻¹² [m ² / N]
S ₁₁ ^P = 12.4 × 10 ⁻¹² [m ² / N]
It was. For S ₁₁ ^P , the value described in Non-Patent Document 1 is used.

FIG. 16 is a graph plotting the relationship between | d ₃₁ | and d ₃₃ of the piezoelectric body relating to the piezoelectric element prepared in the above-described example and comparative example of the present embodiment. The same time the piezoelectric body according to the piezoelectric element of this embodiment in FIG. 16 | d ₃₁ | a region showing the relationship between d _33, and the conventional example to become | the relationship between the d ₃₃ | d ₃₁ The indicated area is added.

Basic configuration of a piezoelectric actuator using the transverse vibration mode of a piezoelectric body. (A-1) Side view of a unimorph type cantilever. (A-2) Top view of A-1. (B-1) Side view of a unimorph actuator. (B-2) B-1 top view. Non-Patent Document 1, the graph of d _33, d ₃₁ for each composition PZT. The figure which shows the pattern at the time of measuring the extreme point of a {110} asymmetric surface by X-ray diffraction. (A) shows a case of a uniaxially oriented crystal having a <100> PZT perovskite structure. (B) shows a case of <100> single crystal having a PZT perovskite structure. It is an apparatus schematic showing the structure and mechanism of an MOCVD apparatus. It is the schematic of the inkjet head to which the piezoelectric element of this embodiment is applied. It is sectional drawing in the width direction of the part containing the piezoelectric material of FIG. It is a figure which shows the structure of 1 unit of an inkjet head. 1 is a schematic diagram of an ink jet recording apparatus according to an embodiment. FIG. 9 is a schematic diagram of an operation mechanism unit with the exterior of the ink jet recording apparatus of FIG. 8 removed. It is a structure sectional view for showing a manufacturing process of an ink jet head of this embodiment. 1 is a diagram illustrating a configuration of an MOCVD apparatus used in forming a piezoelectric body in Example 1. FIG. FIG. 3 is a diagram showing a time sequence in the pulse MOCVD method of the first embodiment. d ₃₁ Measurement sample is shown. (13-1) is a side view showing the layer structure after cutting. (13-2) It is a top view which shows a shape. It is a schematic diagram of a d ₃₃ measurement device. It is a figure for demonstrating _d31 measurement. (15-1) is a schematic view of a unimorph type cantilever displacement measuring apparatus. (15-2) is a schematic diagram showing a basic sample layer structure. The piezoelectric body according to the piezoelectric element of this embodiment | is a graph showing the relationship between the d ₃₃ | d _31.

Explanation of symbols

1001 SOI substrate 1002 Si substrate 1003 SiO ₂ layer 1004 Si (100) layer 1005 (100) YSZ epitaxial film 1006 (100) LNO epitaxial film 1007 (100) SRO epitaxial film 1008 Piezoelectric body 1009 Upper electrode 1011 Individual liquid chamber 1012 Restriction part 1013 Common liquid chamber 1014 Discharge port 1015 Nozzle plate

Claims (8)

In a piezoelectric element having a piezoelectric body and a pair of electrodes in contact with the piezoelectric body, the piezoelectric constants d ₃₃ and d ₃₁ of the piezoelectric body are expressed by the following relational expression (I):
0.1 ≦ | d ₃₃ / d ₃₁ | ≦ 1.8 (I)
The piezoelectric element characterized by satisfy | filling.   2. The piezoelectric element according to claim 1, wherein a film thickness of the piezoelectric body is not less than 1 μm and not more than 10 μm.   3. The piezoelectric element according to claim 1, wherein the piezoelectric body is made of a PZT-based or relaxer-based piezoelectric material.   4. The piezoelectric element according to claim 1, wherein the piezoelectric body is a <100> uniaxially oriented crystal or a single crystal.   5. A diaphragm is further provided on one of the electrodes, an oxide layer is provided on a surface of the diaphragm, and the electrode on which the diaphragm is provided includes at least a conductive oxide layer. The piezoelectric element as described in 2.   6. The piezoelectric element according to claim 5, wherein the electrode provided with the diaphragm has two or more conductive oxide layers.   A liquid discharge head comprising the piezoelectric element according to claim 1. A liquid discharge apparatus comprising the liquid discharge head according to claim 7.

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